1. Field
Aspects of embodiments according to the present invention relate to an inverter and a scan driver using the same, and more particularly, to an inverter capable of improving the reliability of driving and a scan driver using the same.
2. Description of Related Art
Recently, various flat panel displays (FPDs) with reduced weight and volume in comparison to cathode ray tubes (CRT) have been developed. The FPDs include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an organic light emitting display.
Among the FPDs, the organic light emitting display displays an image using organic light emitting diodes (OLEDs) that generate light by re-combination of electrons and holes. The organic light emitting display has high response speed and is driven with low power consumption. In a typical organic light emitting display, current corresponding to data signals is supplied to the OLEDs using transistors formed in pixels so that light is emitted by the OLEDs.
The typical organic light emitting display includes a data driver for supplying the data signals to data lines, a scan driver for sequentially supplying scan signals to scan lines, and a pixel unit including a plurality of pixels coupled to the scan lines and the data lines.
The pixels included in the pixel unit are selected when the scan signals are supplied to the scan lines in order to receive the data signals from the data lines. The pixels that receive the data signals generate light with brightness (e.g., predetermined brightness) corresponding to the data signals and display an image (e.g., a predetermined image).
On the other hand, the scan driver includes stages coupled to the scan lines. Each of the stages includes a plurality of transistors in order to supply the scan signals to the scan lines. P-type (for example, PMOS) or N-type (for example, NMOS) transistors that constitute the stages are formed in a panel together with the pixels. When the stages are formed in the panel together with the pixels, manufacturing cost is reduced.
However, when the stage is realized by N-type transistors, the turn-off operation of the transistors is not satisfactorily controlled due to the threshold voltage Vth shift of the transistors, and an erroneous operation may be caused. That is, in the case of the N-type transistors, the threshold voltage Vth is negatively shifted during operation so that the transistor is not turned off in a state where a voltage Vgs between a gate and a source is about 0V (e.g., Vgs=0V).